The invention relates to a pinch valve with a hose-like valve element having a longitudinal axis, and an actuating element that is disposed on the outer circumference of the valve element and that is rotatable, executing an actuating movement, relative to the valve element in the circumferential direction thereof, and, in addition, having at least one plunger, which while executing an operating movement can be optionally moved toward the inside in the direction of the valve element or, to the opposite, toward the outside, transversely relative to the longitudinal axis of the valve element for the purpose of pinching the valve element more or less intensely and which is disposed between the valve element and the actuating element, and wherein the actuating element at the inner side thereof that is directed toward the valve element includes at least one actuating surface serving for a pressing application of force to the at least one plunger and sliding off the at least one plunger when executing the actuating movement, wherein the actuating surface has a longitudinal profile extending at least in part in the circumferential direction of the valve element with a changing spacing in relation to the valve element.
A pinch valve of this kind is disclosed in U.S. Pat. No. 3,920,215 and contains a longitudinal, hose-like valve element that is surrounded by a housing-type enveloping body and extends between two fluid connections. Disposed coaxially on the enveloping body is an axially immovably fixed actuating element that is, however, rotatable relative to the valve element in the circumferential direction thereof. The enveloping body is radially slotted and interspersed by two radially displaceable plungers that rest, on the one hand, on the outer circumference of the valve element and, on the other hand, on an actuating surface that is configured on the inner side of the actuating element. The actuating surface has a longitudinal profile that is oriented relative to the circumferential direction of the valve element, wherein the radial spacing thereof relative to the valve element is changing over the length thereof. In other words, the course that the actuating surface takes corresponds to the profile of a longitudinal section of a spiral that is disposed at a right angle relative to the valve element. When the actuating element is rotated relative to the enveloping body, and thereby also relative to the valve element, the spiral-like actuating surface slides off the rear of the plunger allocated thereto and presses the same, to a more or lesser degree, radially to the inside.
A disadvantage of the pinch valve that is known from the prior art is the fact that there is a relatively large gear ratio between the rotational movement of the actuating element that functions as the actuating movement and the operating movement of each actuating element that is derived therefrom. Correspondingly, there results a high actuating force. Moreover, intermediate positions of the plunger can only be guaranteed by means of latching steps, which are instrumental in causing impairments, as they result in a certain heaviness of the actuating movement, do not allow for a stepless adjustment of the desired cross-section of flow and are ultimately subject to a relatively high wear and tear.
DE 69232487 T2 discloses a valve closure that operates in the manner of a pinch valve in that it provides that a hose can be locked by means of a radially movable compression element, for example a ball, in that a cam applies force to the compression element; and the cam is configured on the internal surface of a tube-shaped housing part, and a housing part that receives the hose can be screwed onto the same.
U.S. Pat. No. 2,987,292 discloses a pinch valve with a hose that can be pinched by radially movable balls, which can be actuated by means of a rotatable disc. The disc features curved actuating surfaces on the internal circumference thereof for applying force to the balls.